On Wed, Dec 30, 2015 at 12:16:22PM +0100, Martijn Meijering via bitcoin-dev wrote:
> That looks very interesting. But is effectively blocking old clients from
> seeing transactions really safe? After all, such transactions are still
> confirmed on the new chain. A person might try to send a similar
> transaction several times, perhaps with increasing fees in an attempt to
> get it to confirm and end up paying someone several times.

It's very dangerous to simply send multiple transactions in such a way
that they don't double-spend each other; you have no good way of knowing
for sure that you're seeing the longest block chain with software alone.

Competently designed software with fee-bumping wouldn't allow that
mistake to be made; the UX should make it clear that txs sent are still
pending until confirmed or clearly double-spent.

> Maybe we could require the tx version number to be increased as well so
> transactions sent from old clients would never confirm? Perhaps your code
> already includes this idea, I need to look at it more closely.

That can mess up pre-signed transations, e.g. refunds.

-- 
'peter'[:-1]@petertodd.org
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